Vane type piston



Nov. 17, 1942. H, M DODGE 2,302,109

VANE TYPE PISTON Filed May l5, 1940 \\n I4 Fi 9 3 /9 ,9 INVENTOR F1 7. Ey How-ard M Dodge ATTORN EYS Patented Nov. 17, 1942 2,302,109 l vANE mans'roN Howard M. Dodge, Wabash, Ind., assignor to The General TireRubber Company, Akron, Ohio, a corporation of Ohio Application May 15,1940, Serial No. 335,409

8 Claims.

This invention relates to vane type pistons for fluid pressure motors,and in particular to a novel piston construction for vacuum operatedmotors utilized in windshield wipers for vehicles.

It is an object of this'invention to provide a piston of the typementioned in which an effective seal is provided between the piston andmotor chamber wall but in which the contact area between the piston andmotor chamber wall is considerably reduced to provide decreasedIrictional engagement therebetween.

Another object is to provide a piston construction wherein the packingor seal-providing member is a single unit which may be readily appliedto the piston.

A further object of the present invention is to provide a vane typepiston which is simple in design and construction and which may bemanufactured readily and inexpensively.

Other objects and advantages of the present invention will becomeapparent from the following detailed description accompanied by thedrawing, in which like parts throughout the several views are indicatedby the same reference numerals,

In the drawing:

Figure 1 is an elevational view with parts broken away illustrating themotor chamber with the piston mounted therein Fig. 2 is an enlargedelevational view in section of the piston showing details of itsconstruction and assembly;

Fig. 3 is an enlarged fragmentary sectional view taken substantially online 3 3 of Fig. 2, showing how the piston may be secured to its drivingshaft;

Fig. 4 is an enlarged elevational view with partsl broken awayillustrating further details of the piston construction;

Fig. 5 is an enlarged sectional view taken substantially on line 5 5 ofFig. 4, illustrating an improved packing member embodying the presentinvention; and

Fig. 6 is an enlarged sectional view taken substantially on line 66 ofFig. 4, illustrating another view of the packing member.

The fluid pressure motor chamber may best be seen in Fig. 1 andcomprises a semi-cylindrical chamber I having a casing orwall 2 to whichis connected a cover member 3 having formed therein a secondsemi-cylindrical chamber 4 which is concentric with the chamber I. Themember 3 may be secured to the wall 2 in any piston. indicated generallyby the numeral 6, is pivotally mounted intermediate its ends to a shaft"I, the axis of rotation of the shaft coinciding with the axes of thechambers I and 4.

In operation fluid pressure is alternately applied to opposite sides ofthe piston by any suitable means (not shown) to give it oscillatorymovement used for driving a windshield wiper or the like which may beconnected to the shaft 1. The piston proper comprises a flat body whichincludes a pair of rigid members or plates 8 disposed on opposite sidesof the shaft 'l and provided with peripheral flange portions 9 which aredirected toward the opposite plate to give the plates a somewhatcup-shaped appearance. To facilitate proper location of the plates withrespect to the shaft and to aid in securing them thereto, the plates maybe formed with arcuate portions I0 which are apertured to receive asuitable pin or rivet II. To insure that the plates are secured againstmovement and held in generally parallel positions, the plates areapertured at another location to receive a second pin II which passesthrough the plates and through an apertured spacing member I2 shown inFig. 2.

To envelop the plates, and particularly their rim portions, a packingmember or envelope I3, which is preferably constructed from a singlepiece of resilient material such as 'a rubber compound, syntheticrubber, etc., is provided The member I3 is provided with sealing surfaceportions Il at its outer periphery which converge beyond the peripheryof the plates 8 to a crest I5, the crest being disposed approximatelymidway between the planes of the plates and outwardly of the spacebetween the flanges 9 of the' plates 8. Since the sealing portionsextending from both plates are integral and meet at crest I5, suchsealing portion provides a yieldable engagement with the motor chamberwall and is adapted to be depressible into the space between the plates8.

To provide a tight seal around the shaft where it emerges from the sidesof the piston, the flanges 9 at the side portions of the plates 8 may berecessed as indicated at the numeral I6, and the sealing portions I 4are also recessed in this region. Thus, when the piston is inserted intothe motor chamber, the crest I 5 of the sealing portion may be slightlydepressed so that the suitable manner such as by bolts 5. A vane-typeregions of the sealing portion around the shaft that the crest i5 of thesealing portions i4 protrudes slightly beyond the portions of thesealing portions which embrace the shaft when the piston is not in themotor chamber.

To seal. the opposite sides of the piston at the points where the pinsor rivets il pass therethrough, the envelope I3 may be apertured andtightly held to the plate by washers Il which embrace the pins il. Inthis construction the plates may be assembled, the envelope disposedtherearound, the rivets and washers inserted, and the rivets headed sothat the washers slightly compress the sealing member. An alternatemethod of construction would be to secure the plates together by thepins and then dispose the envelope around the plates so that it willcompletely cover one side of the plate and pins. Since it is onlyessential that the periphery of the plates and one side of the platesthrough which the pins extend be covered, the envelope may beconstructed with a large aperture I9 in the' middle of one of the sidesof the plates. This reduces the amount of material necessary forconstructing the envelope and also permits access to the connectionbetween the pins and the plate.

An advantage of the present invention is the provision of a casingstructure or packing member constructed in a single integral unit whichmay be molded or otherwise fabricated from a suitable material. When theenvelope I3 is made of a suitable rubber compound or the like, it may bemolded. In this case it is desirable that the parting line of the moldbe disposed at a point not located at the crest i5 so that an even andconverge between the planes of the plates but uniform crest may beprovided. Such a mold y with a parting line disposed at one side of thethe piston and motor chamber wall is materially decreased. Since thesealing portions are constructed of a resilient material, and further,since they are designed to flex or be depressed into the space betweenthe plates although they are normally urgedtoward the motor chamberwall, a yieldable but positive seal is maintained. In the event that theenvelope or packing member becomes worn by use, it will still maintaincontact with the motor chamber wall because its action is to be urgedthereagainst.

It is to be understood that variations and modifications of the speciiicdevices herein shown and described for purposes of illustration, may bemade without departing from the spirit of the present invention.

What I claim is:

1. A vane type piston for a uid pressure motor which comprises a pair ofspaced plates, a shaft between said plates and adapted to be securedthereto, and an integral resilient packing member adapted to envelop theedge portions of the plates and to extend across the space between theedges of the plates, said member provided with `sealing portionsextending peripherally around the piston beyond the edges of said platesf and depressible into the space between said plates.

2. In a vane type piston having a pair of spaced plates adapted to besecured to a rocker shaft on beyond the side edges of the plates toprovide a relatively small area of contact with the motor chamber walls.

3. In a vane type piston having a pair of spaced plates adapted to besecured to a rocker shaft for pivotal oscillation in a fluid pressuremotor chamber, an integral rim member surrounding the periphery of theplates and embracing the shaft where it emerges from between the plates,said rim member having sealing surface portions converging at theperiphery of the rim to a crest disposed approximately midway betweenthe plates and beyond the periphery thereof, whereby an approximate linecontact may be had between the piston and the motor chamber walls toprovide an effective seal between the opposite sides of the piston whiledecreasing the frictional engagement of the piston with the motorchamber walls.

4. In a vane type piston having a pair of spaced plates adapted to besecured to a rocker shaft for pivotal oscillation in a fluid pressuremotor chamber, an integral rim member surrounding the periphery of theplates and embracing the shaft where it emerges from between the plates,said rim member having sealing surface portions converging at theperiphery of the rim to a crest disposed approximately midway betweenthe plates and beyond the periphery thereof, said crest being adapted toflex toward the space between said plates, whereby an approximate linecontact may be had between the piston and the motor chamber walls toprovide an effective seal between the opposite sides of the piston whiledecreasing the frictional engagement of the piston with the motorchamber walls.

5. A vane type piston pivotally mounted for oscillation in a iiuidpressure motor which comprises a pair of plates adapted to be secured toopposite sides of a rocker shaft, means for securing said plates inspaced relation at another location, an integral member enveloping theperipheral portions of the plates, primary sealing surface portions onsaid member converging at the periphery of the member to a crestdisposed between the planes of the plates but beyond the peripheriesthereof, and secondary sealing portions on said member to seal thepiston in the region of the securing means.

6. A vane type piston comprising a substantially rigid fiat body havingopposite sides terminating in spaced generally parallel peripheralconfronting edge portions providing therebetween a substantiallycontinuous recess about the body, and a single piece resilient envelopeembracing both edges and extending over substantially the entire area ofone side of the body, said envelope being unsupported between said edgeportions 'of the body and having a narrow peripheral sealing crestdisposed between the edge portions and yieldable by bodily movement ofthe envelope into the recess between said edges.

7. A vane type piston comprising a substantially rigid fiat body havingopposite sides terminating in spaced generally parallel peripheraledges, and a single piece hollow sealing member formed of resilientdeformable material, said member being of such shape and size when inunstressed condition as to receive the body internally thereofsubstantially without distortion and having in one side an openingadapted upon distension to pass the body in assembling the piston, theother side of the resilient member being of greater extent than said oneside and substantiallycontinuous over an entire side of the body to sealthe latter.

8. A one piece sealing member for a vane type piston comprising a hollowenvelope structure of resilient molded rubber having generally fiat sidewalls one of which is formed with an opening adapted upon distension topass a rigid piston body in assembling a piston and the other sidewallof which is of greater extent than said one side wall andsubstantially continuous over an entire side of a piston body receivedin the hollow structure, said envelope member having integral edge andend walls connecting the sideV

